It has been known in the art to use dish-shaped, snap-acting bimetallic discs with an electrical contact welded to the disc as contact assemblies. Many of these contact assemblies are part of motor protector devices or the like where the dish-shaped thermostatic bimetallic element provides the actuation means for the device. The protector devices are located typically directly adjacent or inside the motor that the device is protecting to provide inherent protection which senses not only over-current conditions but also over-temperature conditions. Since the contact assemblies are current carrying, both the amount of current flowing through the thermostatic element which provides self-heating as well as the ambient temperature determine if a fault condition occurs and consequently can cause the element to snap to an inverted dish-shaped configuration moving the contact on it away from the other stationary contact of the device.
As such protection devices have been designed to operate under more demanding conditions and at more precise "snap" temperatures, the need for highly reliable devices has been become more important including the snap-acting thermostatic dish-shaped element and contact assembly. Additionally, there is always a need to produce the contact assemblies and thus ultimately the total device more economically. Presently the contacts are provided typically in the form of individual button contacts with weld projections on the bottom for welding the contact buttons to the thermostatic element. Such finished welded assemblies as described in U.S. Pat. No. 3,430,177 assigned to the assignee of instant application and incorporated herein by reference have in general been acceptable but there is a need for a more economically produced assembly with very high reliability especially with regard to failure due to contacts "falling off". It is important that any new device design provides both of these stated objectives and does not disturb disc response.
Accordingly, it is an object of the present invention to provide an improved bimetallic contact assembly for use in a protector switch device or the like.
Another object of the invention is to provide a protector device of which the parts thereof are suitable for mass production techniques.
Still another object of this invention is to provide a protector device with an improved bimetallic contact assembly which is reliable in operation and economical to produce.
Yet another object of this invention is to provide a method for producing the improved bimetallic contact assembly of this invention.
Other objects and features of the invention will become more readily understood from the following detailed description and appended claims, when read in conjunction with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof.